# Sumibi - AI Japanese Keyboard — Romaji to Natural Japanese

> Romaji to Natural Japanese (iPhone/iPad app by kiyoka nishiyama.)

- Source: https://appshunter.io/ios/app/sumibi-ai-japanese-keyboard/id6798280948 (this page in markdown: same URL + `.md`)
- Developer: [kiyoka nishiyama](https://appshunter.io/developer/6798280950)
- Category: Utilities, Productivity
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: Japanese
- Released: 2026-08-17
- Data updated: 2026-10-01

## What is Sumibi?

Sumibi is a custom iPhone keyboard that uses AI to convert sentences typed in romaji into natural Japanese.

Type with a single English QWERTY layout and tap Convert. You can enter Japanese without switching to a kana keyboard, while ordinary English typing remains available on the same keyboard.

KEY FEATURES
• Convert romaji sentences into natural Japanese
• Use one QWERTY layout without switching to a kana keyboard
• Convert only a selected range while leaving surrounding text unchanged
• Request additional candidates, including different kanji and expressions with the same reading
• Restore the original text with Undo
• Register preferred product names and proper nouns in a user dictionary
• Save up to three writing-style presets for language, tone, punctuation, or formatting
• Compare results with and without a writing-style prompt before saving it
• Review conversion counts, token usage, and estimated API cost by model
• Enter numbers and symbols without leaving the Sumibi keyboard
• Configure haptic feedback and key-click sounds

REQUIREMENTS
AI conversion requires an OpenAI-compatible API endpoint, model name, and API key supplied by the user. API charges and terms are determined by the selected API provider and are not included with the Sumibi download.

To use network conversion, add Sumibi in iOS keyboard settings and enable Allow Full Access. Without Full Access, ordinary QWERTY typing, delete, space, return, symbols, and keyboard switching remain available, but AI conversion is disabled.

PRIVACY
AI conversion occurs only after the user reviews the destination and explicitly consents to sending data to the selected third-party AI service. When Convert is tapped, the selected text, the minimum surrounding context needed for conversion, the registered user dictionary, and the active writing-style prompt are sent to the displayed API endpoint.

Data does not pass through a server operated by the Sumibi developer. Sumibi does not store keystrokes, source text, the user dictionary, or API keys on a developer-operated server. The API key is stored in the device Keychain and is not synchronized through iCloud. Processing and retention by the destination service are governed by the selected API provider's terms.

The app's settings interface and help text are currently in Japanese.

Sumibi is open-source software.

## Is Sumibi safe?

Not enough ratings yet to assess Sumibi.

## Is Sumibi legit?

Sumibi - AI Japanese Keyboard has limited verification signals. The AppsHunter Legitimacy Score for Sumibi is 58 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 3 releases)

### 1.2.0 — 2026-09-15

• Added writing-style presets for output language, tone, punctuation, and formatting
• Added Ember Glass effects to conversion controls on iOS 26 and later
• Improved key, candidate-selection, and conversion-state animations
• Refined delete-key repeat timing and key-press responsiveness
• Improved usability and stability

### 1.1.0 — 2026-08-20

・選択中の文字列だけをAIで変換できる「範囲を変換」を追加
・モデルごとの変換回数、入出力トークン数、概算利用料金を確認できる利用状況画面を追加
・「さらに変換候補を取得」で、同じ読みを持つ別の漢字や表現をこれまでより幅広く提案
・保存済みAPIキーの末尾4文字を表示し、使用中のキーを確認できるよう改善
・範囲選択した文字列を直接変換できるようになったため、クリップボードからの読込機能を廃止
・その他、ユーザビリティを改善

### 1.0.0 — 2026-08-17

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-01.*